After you install Toolbox 4.1, there is a background procedure during the first launch of the system. This procedure multiplies the EPI Suite calculators based on the number of processor cores in order to optimize calculation times when such are needed. In some cases, this process may take longer than usual and may cause the Toolbox Client to display the message that it cannot connect to the server. In this situation we recommend to wait at least 10 minutes and to try launching the Toolbox again.
The above described background process is initiated by the Toolbox Server (ToolboxServerApp.exe) which might have been seen by your antivirus system as a malicious activity (multiplying files in the background). To avoid such situations, we have signed the executable with our certificate to confirm that it comes from a trusted developer and that it has not been corrupted since signed. However, in your case, this has not stopped your antivirus system from deleting it. What we can recommend in this case, is to ask your IT department to whitelist the ToolboxServerApp after scanning it themselves.